#include <stdio.h>
#include <assert.h>
char* my_strcat(char* a,const char* b)
{
	char* ret = a;
	assert(a && b);
	while (*a != '\0')
	{
		a++;
	}
	while (*a++ = *b++);
	return ret;
}
int main()
{
	char arr[20] = { 0 };
	char arr1[] = "world";
	my_strcat(arr, arr1);
	printf("%s\n", arr);
	return 0;
}